diff options
| author | Michael Pratt <mpratt@google.com> | 2022-07-20 11:09:14 -0400 |
|---|---|---|
| committer | Michael Pratt <mpratt@google.com> | 2022-08-02 18:50:55 +0000 |
| commit | 7e952962dff6aafb9ed888a86a7208f01fbe9508 (patch) | |
| tree | 839d6f682c0472250da1dbe12fe39ae7b1b5b363 | |
| parent | 9dbc0f3556b3401b0f3339d4c33cd32ea16d5241 (diff) | |
| download | go-7e952962dff6aafb9ed888a86a7208f01fbe9508.tar.gz go-7e952962dff6aafb9ed888a86a7208f01fbe9508.zip | |
runtime: clean up canpanic
* The gp argument to canpanic is always equivalent to getg(), so no need
to pass it at all.
* gp must not be nil or _g_.m would have crashed, so no need to check
for nil.
* Use acquirem to better reason about preemption.
Change-Id: Ic7dc8dc1e56ab4c1644965f6aeba16807cdb2df4
Reviewed-on: https://go-review.googlesource.com/c/go/+/418575
Reviewed-by: Austin Clements <austin@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Michael Pratt <mpratt@google.com>
| -rw-r--r-- | src/runtime/os_js.go | 2 | ||||
| -rw-r--r-- | src/runtime/os_plan9.go | 2 | ||||
| -rw-r--r-- | src/runtime/panic.go | 19 | ||||
| -rw-r--r-- | src/runtime/signal_unix.go | 2 | ||||
| -rw-r--r-- | src/runtime/signal_windows.go | 2 |
5 files changed, 15 insertions, 12 deletions
diff --git a/src/runtime/os_js.go b/src/runtime/os_js.go index 34cc0271f0..7fbeb5a832 100644 --- a/src/runtime/os_js.go +++ b/src/runtime/os_js.go @@ -50,7 +50,7 @@ const _SIGSEGV = 0xb func sigpanic() { g := getg() - if !canpanic(g) { + if !canpanic() { throw("unexpected signal during runtime execution") } diff --git a/src/runtime/os_plan9.go b/src/runtime/os_plan9.go index f0e7c6ae70..b86bd6b3a9 100644 --- a/src/runtime/os_plan9.go +++ b/src/runtime/os_plan9.go @@ -76,7 +76,7 @@ func os_sigpipe() { func sigpanic() { g := getg() - if !canpanic(g) { + if !canpanic() { throw("unexpected signal during runtime execution") } diff --git a/src/runtime/panic.go b/src/runtime/panic.go index 121f2022a4..ab8d1f82b4 100644 --- a/src/runtime/panic.go +++ b/src/runtime/panic.go @@ -1290,29 +1290,32 @@ func dopanic_m(gp *g, pc, sp uintptr) bool { // panicking. // //go:nosplit -func canpanic(gp *g) bool { - // Note that g is m->gsignal, different from gp. - // Note also that g->m can change at preemption, so m can go stale - // if this function ever makes a function call. - _g_ := getg() - mp := _g_.m +func canpanic() bool { + gp := getg() + mp := acquirem() // Is it okay for gp to panic instead of crashing the program? // Yes, as long as it is running Go code, not runtime code, // and not stuck in a system call. - if gp == nil || gp != mp.curg { + if gp != mp.curg { + releasem(mp) return false } - if mp.locks != 0 || mp.mallocing != 0 || mp.throwing != throwTypeNone || mp.preemptoff != "" || mp.dying != 0 { + // N.B. mp.locks != 1 instead of 0 to account for acquirem. + if mp.locks != 1 || mp.mallocing != 0 || mp.throwing != throwTypeNone || mp.preemptoff != "" || mp.dying != 0 { + releasem(mp) return false } status := readgstatus(gp) if status&^_Gscan != _Grunning || gp.syscallsp != 0 { + releasem(mp) return false } if GOOS == "windows" && mp.libcallsp != 0 { + releasem(mp) return false } + releasem(mp) return true } diff --git a/src/runtime/signal_unix.go b/src/runtime/signal_unix.go index 0be499b2e9..a220f8347e 100644 --- a/src/runtime/signal_unix.go +++ b/src/runtime/signal_unix.go @@ -815,7 +815,7 @@ func sighandler(sig uint32, info *siginfo, ctxt unsafe.Pointer, gp *g) { //go:linkname sigpanic func sigpanic() { g := getg() - if !canpanic(g) { + if !canpanic() { throw("unexpected signal during runtime execution") } diff --git a/src/runtime/signal_windows.go b/src/runtime/signal_windows.go index c5cf38c5c2..f732d1d5c0 100644 --- a/src/runtime/signal_windows.go +++ b/src/runtime/signal_windows.go @@ -245,7 +245,7 @@ func winthrow(info *exceptionrecord, r *context, gp *g) { func sigpanic() { g := getg() - if !canpanic(g) { + if !canpanic() { throw("unexpected signal during runtime execution") } |